_1003.java

packagecom.fishercoder.solutions.secondthousand;

importjava.util.ArrayDeque;
importjava.util.Deque;

publicclass_1003 {
publicstaticclassSolution1 {
publicbooleanisValid(StringS) {
Deque<Character> stack = newArrayDeque<>();

for (charc : S.toCharArray()) {
if (c == 'c') {
if (stack.isEmpty() || stack.pop() != 'b') {
returnfalse;
 }
if (stack.isEmpty() || stack.pop() != 'a') {
returnfalse;
 }
 } else {
stack.push(c);
 }
 }

returnstack.isEmpty();
 }
 }
}